Color-photographic bleach out dyestuff layers



Patented July 28, 1936 PATENT OFFICE COLOR-PHOTOGRAPH) BLEACH OUTDYESTUFF LAYERS Bla Gaspar, Brussels, Belgium No Drawing. ApplicationDecember 29, 1932,

Serial No. 649,442. 1932 '7 Claims.

This invention relates to a method of producing color-photographicbleach-out dyestufi layers. Attempts to produce color photographicimages by bleaching processes are very old, and

5 innumerable variations of this process have been proposed. Veryappreciable results have been obtained in this direction, butnotwithstanding it has not been possible to make the finished imagescorrespondingly durable. In particular 10 there have been used for thispurpose practically without exception basic dyestuffs. Reference iscertainly contained in the literature to the effect that on occasionsubstantive or acid dyestuffs have also been investigated for the-pur-15 pose in question, thus for example by Valenta in the PhotographischeRundschau, 1911, page 56 etc.-, but the results obtained were not of auseful kind, because the bleaching action was too slow. Indications havealso been furnished from other sources, but these related in themselvesto dyestuffs extremely unfast in light.

The surprising fact has been discovered that the bleaching, i. e. thelight-sensitiveness of acid dyestuffs, which in themselves are lastingin light, 25 may be very considerably increased if in addition to adesired sensitizer there is also introduced into the layer a suitableauxiliary body, which activates the sensitizer. As auxiliary body thereare employed the acid salts of multi-base acids, organic or inorganicacids or acid or reducing substances, such as phenols. or aminophenols,and more particularly those which are suitable as photographicdevelopers. An extremely high sensitiveness to light is obtained, if adurable double compound of hypo-sulfurous acid is employed, for examplesodium formaldehyde sulfo oxalate or its double metal salts. Thesecompounds may be employed either alone as sensitizers or also admixedwith other sensitizers. As additional auxiliary bodies there areemployed metal salts having a catalytical action, for example vanadiumor titanium salts. Inorganic sulfur compounds, such as sulfides orsulfites may be incorporated'in the layer.

Example 1 In Germany January 4,

tion is apparent after approximately 10 minutes, which action continuesup to complete bleaching.

Example 2 Tartrazine is mixed with thiosinamine and sul- 5 A. 100grammes water 5 grammes thiosinamine 25 grammes 20% sodium bisulfatesolution- The sensitizing effect, which in itself is of a powerful kind,may be further increased by the addition of 1 gramme monomethylparamidophenol sulfate. Y

B. 200 grammes water 5 grammes rongalite 5 grammes thiocarbamide Thereare employed for 4 com. gelatine 4%, approximately com. 1% dyestuifsolution and A; com. sensitizer to 1 qdm.

Example 3 For a three-color image there are employed I for exampleTartrazine, Patent Blue A, Fast Red D in mixture with a colloid, forexample gelatine, in conjunction with one of the sensitizers set forthabove.

The process according to the invention reveals the particular advantage,that, as compared with the dyes hitherto in use, dyestuffs may beemployed which are extremely fast in light, and after the fixing anadditional bleaching of the dyestuff does not take place. The dyestuffsemployed in accordance with the invention possess the advantage that thesubstantive dyestuffs remain adhering to the fibres of the paper, orsingle substantive dyestufl's and also the acid dyestuffs impregnate thegelatine in such fashion 5 that the same cannot be-washed out or onlywith extreme difficulty. The fixing of the bleached images isaccordingly very simple. The images are washed subsequently in water, asa result of which the sensitizer is dissolved away and them dyestufiremains adhering to the backing or support or in the binding agent (forexample in the gelatine), and cannot be washed out-or at least only withextreme dificulty. There may also be performed subsequently a shortaftertreatment in copper sulfate or alum or in another mordant formingmeans for the purpose of increasing the fastness in light.

The dyestufis may be employed in mixture or also poured in the knownmanner on to superimposed layers. For copying purposes there areemployed either tripack images or other master images or color-screenimages as desired.

It has been found that large-grain screen images may be copiedparticularly well, as in this case parallactic errors and whitening ofthe colors are unable to occur.

Suitable dyestuffs are, for example, Diamine Pure Blue FF, Tartrazine,New Patent Blue, Phloxine B B N, Xylene Light Green 63, Patent Blue,Chromium Green GD extra, Guinea Blue, Fast Red D, Chloramine Light Red 7BL, Chromium Fast Red BD paste, Geranine, Complementary Red D, PinatypeBlue D, Xylene Fast Blue FF.

The index numbers of the dyes quoted in the foregoing examples are setforth in Schultz Dyestufi! Tables, Berlin, 5th Ed., 1920, as follows:-

Chloramine Light Red 73L No number found (manuiactured by Sandor, Basel,Swi mrland). Tartraziue 23 Patent Blue 545 Fast Red D 168 Diamine PureBlue FF 424 New Patent Blue 663 Phloxine 596 Chromium Fast Red BDSchultz, page 379 (no number). Geranine 118 Complementary Red Mentionedin the "Pine Handbuch" oi the I. G. Farbenindustrie A.-G. l 'inatypeBlue Do. Xylene Light Green GB No number (manufactured by Sandor,Basel). Xylene Fast Blue 0. Chromium Green GD extra 609 Guinea Blue Itwill be understood that no restriction is made to the particularexamples described in the above or to the specific samples quoted, andthat numerous modifications and substitutions are quite possible withinthe meaning of the above description and the annexed claims withoutdeparting from the spirit of the invention.

I claim:--- 1. Photographic bleach-out layers comprising a colloidalcarrier fastly dyed by at least one acid azo-dyestuff and havingincorporated in addition a sensitizer and an agent activating the saidsensitizer, one at least of the additions being dischargeable.

2. Photographic bleach-out layers comprising a colloidal carrier fastlydyed by at least one acid azo-dyestufl and having incorporated inaddition a sensitizer and a substance of acid reaction'activating thesaid sensitizer, one at least of the additions being dischargeable.

3. Photographic bleach-out layers comprising a colloidal carrier fastlydyed by at least one acid azo-dyestufl and having incorporated inaddition a sensitizer and a reducing substance activating the saidsensitizer, one at least of the additions being dischargeable.

4. Photographic bleach-out layers comprising a colloidal carrier fastlydyed by at least one acid azo-dyestufl and having incorporated in one atleast of the additions being dischargeable. o

'7. Photographic bleach-out layers comprising a colloidal carrier fastlydyed by at'least one acid azo-dyestufl and having incorporated inaddition a compound of the thio-urea-group and a substance of acidreaction, one at least of the 45 additions being dischargeable.

BELA GASPAR.

